def _odd_iter():
    n=1
    while True:
        n = n + 2
        yield n

def _not_divisible(n):
    return lambda x:x%n>0

def primes():
    yield 2
    it = _odd_iter()
    while True:
        n=next(it)
        yield n
        it = filter(_not_divisible(n),it)

for n in primes():
    if n<1000:
        print(n)
    else:
        break